深度遍历有向图

问题：用标记来记录是否访问过，这个是个关键点。当然也可以用栈，思想是每访问一个顶点就入栈，接着访问这个顶点的下一个顶点，最后出栈，看出栈的顶点有没有下一个顶点，如果有就继续访问。如此重复，直到栈空。

还有一点就是用到了递归思想。很像二叉树的前序遍历。

代码：

#include <iostream>

#include <cstdlib>

using namespace std;



#define MAXV 20



typedef struct edgeNode

{

	int data;

	struct edgeNode *next;

}edgeList;



typedef struct headNode

{

	char vex;

	edgeList *firstNode;

}headList;



typedef struct graph           //定义邻接表结构

{

	headList arr[MAXV];

	int v,e;

}*adjGraph;





void createAdjGraph(adjGraph &ag)

{

	char c;

	int p,q;

	edgeList *s;

	cout<<"please input the num of v and e:";

	cin>>ag->v>>ag->e;



	for(int i=0;i<ag->v;i++)             //初始化头节点

	{

		cout<<"please input vex:";

		cin>>c;

		ag->arr[i].vex=c;

		ag->arr[i].firstNode=NULL;

	}



	for(int j=0;j<ag->e;j++)

	{

		cout<<"please input two vexs:";

		cin>>p>>q;

		s=(edgeList *)malloc(sizeof(struct edgeNode));

		s->data=p;

		s->next=ag->arr[q].firstNode;

		ag->arr[q].firstNode=s;

	}

}



void showAdjGraph(adjGraph ag)

 {

	for(int i=0;i<ag->v;i++)

	{

		cout<<ag->arr[i].vex<<"  ";

		while(ag->arr[i].firstNode!=NULL)

		{

			cout<<ag->arr[i].firstNode->data<<" ";

			ag->arr[i].firstNode=ag->arr[i].firstNode->next;

		}

		cout<<endl;

	}

}



void DFS(adjGraph ag,int v,int *visited)

{

	 edgeList *s;

	 int w;

	 visited[v]=1;

	 s=ag->arr[v].firstNode;

	 cout<<ag->arr[v].vex<<"->";

	 while(s!=NULL)

	 {

		 w=s->data;

		 if(visited[w]==0)

			 DFS(ag,w,visited);

		 s=s->next;

	 }

	 

}

void DFSTraversal(adjGraph ag)

{

	int visited[MAXV];



	for(int i=0;i<ag->v;i++)

	{

		visited[i]=0;

	}



	for(int j=0;j<ag->v;j++)

	{

		if(visited[j]==0)

		   DFS(ag,j,visited);

	}

	cout<<endl;

}

int main()

{

	adjGraph ag;

	ag=(adjGraph)malloc(sizeof(struct graph));

	cout<<"创建图:"<<endl;

	createAdjGraph(ag);

	cout<<"输出图"<<endl;

	showAdjGraph(ag);

	cout<<"深度遍历图:"<<endl;

	DFSTraversal(ag);

	return 0;

}

 运行结果：